Method and means for corrosion protection of cables exposed to underground environments

ABSTRACT

Stranded cable such as flexible pumping strand used for oil wells is protected from deterioration in corrosive underground and underwater environments by jacketing the cable with a plastic sheath and pumping a corrosion-inhibiting liquid having a specific gravity similar to that of the immediate underground environment from the surface through the strand and out the lower end of the strand while maintaining a slight positive pressure within the strand or cable.

United States Patent 151 3,637,341 Horton et al. 51 Jan. 25-, 1972 [54]METHOD AND MEANS FOR 2,593,057 4/1952 Savoy ..2l/2.7 X I 2,654,43610/1953 Carl1sle et a1... ...l66/310 CORROSION PROTECT 0N 0F CABLES2,769,921 1 1/1956 Nahin et a1 ..21/2.$ X EXPOSED To UNDERGROUND2,770,307 11/1956 Deerdoff ..l66/3l0 x ENVIRONMENTS 2,803,259 8/1957Pesnell ..166/3|0 x 2 926 066 2/1960 Lew ..2l/2.5 [72] Inventors: JamesB. Horton, Bethlehem; Herbert E.

Townsend, Jr Hellenown both of Pa 3,497,990 3/1970 Jeffnes ..2l/2.7 X[73] Assignee: Bethlehem Steel Corporation FOREIGN PATENTS 0RAPPLICATIONS 22 Filed; Dec. 29 19 9 293,835 8/1929 Great Britain..21/2.5 pP 888,551 Primary Examiner-MorrisO. Wolk AssistantExaminer-Barry S, Richman 52 us. c1 ..21/2.s, 21/27, 21/61, Ammey-hsePhoKeefe 166/310 511 1m. 01 ..c231 11/00023 1 1/08 [571 ABSTRACT [58]Field olSearch ..21/2.5, 2.7, 61; 166/310 stranded cable such asflexible pumping Strand used for O wells is protected from deteriorationin corrosive underground References Clted and underwater environments byjacketing the cable with a plastic sheath and pumping acorrosion-inhibiting liquid hav- UNITED STATES PATENTS ing a specificgravity similar to that of the immediate un- Re 23,583 11/1952 Eilerts..21/2.7 X rg n nvir nment from he surface through the strand 1,227,0875/1917 Steffens..... .2l/2 5 UX and out the lower end of the strandwhile maintaining a slight 2,510,771 6/1950 B d t 2 1/25 X positivepressure within the strand or cable. 2, 8 9190 1 ..2l2.5X

523 89 l 5 Car son l l8 Clalms, 4 Drawing Figures 4/ O 27 o 3/ oPATENTED JAI25 1912 SHEU 10F 2 WAWAVWW/WV/AWAV INVENTORS James B. HorfonHerberf E. Townsenddr BACKGROUND OF THE INVENTION This invention relatesto the protection of wire cable including both wire strand and rope fromcorrosive environments.

Steel strand and rope used in subatmospheric environments such as underthe sea and within deep oil wells and the like is frequently subject toextremely rapid and severe corrosion. Such corrosion may take the formof corrosion fatigue or stress corrosion, hydrogen sulphide cracking andother specialized forms of corrosion as well as general surfacecorrosion. Such corrosion necessitates frequent inspections andreplacements of the strand or rope, usually at considerable expense andinconvenience due to interrupted operations. The corrosive brinefrequently present in oil wells, for instance, may make replacementnecessary only a month or two of operation of the strand in a well. Evenmore serious, certain forms of corrosion such as stress corrosion andthe like may be difficult to detect by mere inspection and if notdetected 'may cause sudden hazardous failures of the strand or rope.

Various schemes for protecting such ropes and strands from the corrosiveenvironment have been tried, notably encapsulation of the strand andrope in various plastics and combinations of plastics. Unfortunately,plastics in general, while being in many cases fairly corrosionresistant themselves, and substantially waterproof over short periods,are over longer periods significantly permeable to many fluids and othersubstances including a great number of corrosive substances.Consequently while a plastic coating is often a very effective corrosionprotection for short periods, if the strand or rope is continuouslyimmersed in the corrosive environment over substantial periods of timeconsiderable quantities of corrosive substances may reach the metallicportions of the cable. Corrosion inhibitors may occasionally be enclosedwith the strand or rope within the plastic encapsulation but suchcorrosion inhibitors are soon exhausted by the sheer quantities ofcorrosive substances which may make their way through the plasticcoating over a period of time. In addition the normal permeability tothe environment of the plastic coating may be aggravated by injuriessuch as abrasions and minor ruptures of the plastic coating whichaccelerate the admittance of the corrosive environment. Unavoidablemanufacturing defects such as holidays or the like in the plasticcoating may also at times cause serious difficulties.

The present invention obviates the foregoing difficulties of othercorrosion protective systems.

SUMMARY OF THE INVENTION The present invention protects metal cable suchas wire strand and rope from highly corrosive environments by theprovision of a plastic or flexible jacket about the surface of the cableand the introduction into and through the cable in the intersticesbetween the wires of a corrosion-inhibiting liquid having a specificgravity substantially at least as great as or similar to the specificgravity of the principal fluid component of the environment at apositive pressure with respect to the environment and at a ratesufficient to replace an amount of the corrosion-inhibiting liquid whichis allowed to escape from the'ter'minal end of the cable and along anyother permeable portions of the cable. In this manner the corrosioninhibitor is continuously renewed so that the metal surfaces arecontinuously protected by fresh corrosion inhibitor while the entranceof corrosive substances into the cable is opposed by the outflow of thecorrosion inhibiting fluid.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically shows a corrosioninhibiting system according to the present invention.

FIG. 2 is a chart illustrating the normal expected specific gravities,or densities, of different naturally occurring environments.

FIG. 3 is a graph illustrating allowable differentials between thespecific gravities, or densities, of the environment andcorrosion-inhibiting liquids.

FIG. 4 shows an enlarged and partially cutaway section of a preferredform of strand for use in the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 is shown a schematicview of an oil well 11 including a well casing 13, a differentialpressure or other suitable pump 15 positioned at the bottom of saidcasing to pump the oil up to the surface through the casing, a flexiblepumping strand [7 comprised of individual steel wires 19 and a nylonplastic jacket 21 covering the strand. The flexible pumping strand 17passes at the wellhead 23 through the usual packing 25 preferably beingprotected atthis point by a so-called hollow polished rod 26 which issecured to the strand and reciprocates in the packing 25 as the flexiblepumping strand 17 is reciprocated by the movements of a horsehead 27operated at the surface by motor 29 through connecting rod 31 connectedto flyweight arm 33. The reciprocation of flexible pumping strand 17serves to operate pump 15 to which the flexible pumping strand isattached through a swaged fitting 3S, shear release 37 and connectingpony rods 39. Hollow polished rod 26 and strand 17 may preferably besupported form horsehead 27 by carrier bar 34 through bridles 36. Excessflexible pumping strand I7 is reeled on a reel 41 secured to thesupporting framework 43 upon which horsehead 27 is pivoted.

It will be understood that the well shown in FIG. 1 may be severalthousand feet deep and will be filled with crude oil which is in manycases saturated with many highly corrosive salts and gaseous substances,some in the oil and some or most dissolved in water or brine mixed withthe crude oil. Different wells will contain different corrosivesubstances which may bepredominantly acid or alkali and otherwise varydepending upon the nature of the surrounding geological strata.

Not only is the well 11 likely to be filled with corrosive substancesbut it is also subjected, particularly in the lower portions, to veryhigh pressures due to the great height of superimposed liquid in thewell. These pressures not only aggravate the permeation of the plasticjacket 21 with the corrosive substances but may also tend to force anycorrosion inhibitors originally contained in the strand away from theareas of greatest pressure. The usual increase in temperature of about 1C. for every increase in depth of feet also aggravates the permeation ofcorrosive substances through the jacket.

At the surface adjacent to horsehead 27 and motor-29 is a reservoir 45of a suitable liquid corrosion inhibitor 47. Corrosion inhibitor 47 maybe composed of some inert liquid which will shield the metal surfaces ofthe wires from corrosive substances or may comprise a substance whichwill oppose corrosion of the wires by reacting itself with the corrosivesubstances or with corrosion products of these substances thus opposingfurther corrosion. It may also. comprise a polar substance which clingsto and coats the wires of the strand shielding them from contact withcorrosive substances. The type of corrosion inhibitor must be chosen tooppose the fonn of corrosion most prevalent in the particular well. Someof the most suitable corrosion inhibiting substances for use with thepresent invention when it is used in oil wells are aqueous solutions ofsodium or other borates, chromates, carbonates and nitrites. This list,however, is by no means exclusive.

For general corrosion protection in water, for instance, sodiumhydroxide, sodium phosphate, various sodium silicates, sodium borates,sodium benzoates, sodium cinnarnate, chromates, nitrites, molybdates andtungstates have all been reported as effective. For corrosion in crudeoil the use of formaldehyde, chromates, sodium bicarbonate, sodiumsilicate, cyanamides, arsenic compounds, aliphatic fatty acid derivatives, imidazolines, rosin derivatives and other substances have beenreported to be effective. Corrosion fatigue has been reportedcounteracted by dodecyl alcohol, dodecyl alcohol and water, octylalcohol, dodecylamine, octadecylamine, nhexadecane and other substances.Stress corrosion cracking in H,S has been found to be retarded orsubstantially eliminated in formaldehyde, ammonia and amines whilefretting corrosion has been decreased by the use of molybdenum sulphideand low-viscosity oil. Combinations of these and othercorrosion-inhibiting materials can effectively be compounded to meet themany and special corrosion problems which are posed by particularcorrosive environments.

For deep marine environments such as are encountered by deep sea mooringcables and the like the corrosion-inhibiting substances should be cheapand effective in small quantities or concentrations, or, alternatively,require only small amounts of corrosion inhibitor to neutralize thecorrosion encountered in the environment. Sealants included within thecorrosion-inhibiting liquid may effectively decrease the amount ofcorrosion inhibitor used by aiding in sealing small abrasions and otherimperfections in the cable jacket.

For use in oil well environments the corrosion inhibitor should not besignificantly detrimental, at least at low concentrations, to furtherrefining operations to be carried on with respect to the crude oil andshould preferably be fairly cheap and conveniently available. Thespecific gravity of the corrosion inhibitor must also be fairly close tothe specific gravity of the oil and water mixture in the well and willpreferably have a slightly greater specific gravity. An aqueous solutionor emulsion of a corrosion-inhibiting agent thus will often serve verysatisfactorily in a well filled with a mixture of crude oil and water oreven in a well filled only with corrosive crude oil as its specificgravity will be slightly greater than the surrounding oil mixture withthe advantages which will hereafter become evident. Gases will not besuitable as corrosion inhibitors in deep subatmospheric environmentsbecause of their low specific gravity or density. Liquid corrosioninhibitors are also likely to be more effective than gases in excludingother liquid corrosive substances from a cable particularly where thecorrosive substances from the external environment are subjected to aconsiderable head or premure. Emulsions of oil and water or water andother liquids may be effective to compound a liquid vehicle fordissolved corrosion-inhibiting substances close to the density of thesurrounding corrosive environment.

A pump 49 located adjacent to reservoir 45 and connected by pipe 51 withthe reservoir is operated by a belt connection to motor 29, which motorfunctions in the first instance principally to operate horsehead 27. inthe alternative, pump 49 may be operated by suitable connections tohorsehead 27 or by an independent motor. Pump 49 serves to introducecorrosion-inhibiting liquid 47 from reservoir 45 into flexible pumpingstrand 17 through tubing 53 connected to flexible pumping strand [7 atany suitable location such as, for instance, above wellhead 25 and belowcarrier bar 34 as shown in FIG. I and force it with a slight positivepressure towards the termination of strand 17 at pump at the bottom ofwell 11. The corrosion inhibitor 47 could also be introduced into theextreme upper end of the flexible pumping strand 17. Preferably thereis, provided a small exit orifice 55 near the termination of strand 17in fitting 35 secured to pony rod 39. Orifice 55 serves as an outlet forcorrosion inhibitor liquid 47 which has passed through the strand 17.There is thus maintained a slight but steady flow through the strand sothat fresh inhibitor will always be present within the strand. If theplastic jacket 21 is permeable enough to the corrosion inhibitor alongits length the orifice 55 may not be necessary to maintain an adequateflow of the inhibitor through the strand, or alternatively, if theplastic is not very permeable to the particular corrosionproducingsubstances in the well a fairly small flow of inhibitor through thecable may be satisfactory. In either event insufficient corrosioninhibitor will be discharged into the crude oil to significantly affectsubsequent refining operations.

if the corrosion inhibitor liquid has a higher specific gravity than thesurrounding fluid medium in the oil well the weight of the liquid headthrough the strand 17 will aid in establishing sufficient flow throughthe strand. In a deep well, however, the specific gravity cannot besignificantly greater than the specific gravity of the environment, elsethe weight of the column of corrosion inhibitor within the strand mayresult in such a high positive pressure within the strand near thebottom of the well as to overcome the strength of the plastic jacket 21causing ballooning, rupture, or other damage to the jacket. 0n the otherhand, if the specific gravity of the corrosion inhibiting liquid issignificantly less than the specific gravity of the surroundingenvironment, fluid pump 49 will be required to apply a high positivepressure to the corrosion-inhibiting liquid 47 to counteract the highpressures in the deeper portions of the well where the pump 15 islocated. High positive pressures near the top of the strand where theexternal pressure is less, however, may cause the plastic outer jacketto balloon and eventually fail in these upper portions. It will thus beseen that when a plastic-jacketed pumping strand or other flexiblyjacketed cable is to be used in deep subatmospheric environments with acontinuously renewed flow of corrosion inhibitor it is necessary thatthe specific gravity of the corrosion inhibitor be substantially similarto and preferably at least as great as the specific gravity of theimmediately surrounding environmental fluid. Preferably the specificgravity of the corrosion-inhibiting liquid will be somewhat but not toomuch greater than that of the surrounding environment. Otherwise itwould be necessary to provide some form of armored casing to contain thedifferential pressures. Thus the use of fluids such as inert or reducinggases as corrosion inhibitors in subatmospheric applications beloweither the surface of the land or of the sea is not practical at anysignificant depth. It is absolutely essential in a practical deepapplication corrosion system that the specific gravity of thecorrosion-inhibiting liquid be substantially the same as or at least notdiffer greatly from that of the surrounding fluid medium. In mostinstances the corrosion-inhibiting liquid will have a specific gravityof about 0.85 to 1.2 and more usually from approximately 0.95 to 1.05 oreven 1.10 since the principal surrounding fluid in both the sea and inmost deep wells is comprised principally of either crude oil, crude oiland water plus dissolved salts, or water in the liquid state withvarious dissolved salts. In many cases it may be desirable to have theinhibitor liquid somewhat more dense than the surrounding medium inorder to compensate for head loss due to flow resistance through thestrand. It must be strongly stressed, however, that the exact specificgravity, or density, of corrosion fluid to be used, including anypumping heads for overcoming densities less than that of theenvironment, will ultimately be selected so that the differentialdensity of the corrosion inhibitor with respect to the environment willavoid ballooning, rupture or other damage to the plastic jacket for thelength of strand involved. Thus it will be seen that the densitydifference between the corrosion inhibitor and the surrounding mediummay be allowably greater for shorter strands than for longer strands. Afairly evenly matched density differential is also useful in savingenergy in pumping the corrosion-inhibiting fluid to great depths.

H6. 2 is a bar graph showing the ranges of specific gravities-expressedas the density of the various substances in grams per cubiccentimeterwhich may be expected to be encountered in subsurfaceapplications. For use in the sea the range of expected normal specificgravities will be from about 1.01 to 1.02. in oil wells the possiblerange of environmental specific gravities will be from approximately0.87, the specific gravity of substantially pure crude oil, to 1.2, thespecific gravity of a 26 percent saturated sodium chloride or brinesolution. Normally, of course, the specific gravity of the fluid orenvironment encountered in an oil well will lie well within the morecentral portions of this range, usually within a range of0.95 to 1.05.

The range of specific gravities for most liquids wili range anywherefrom 0.8, the specific gravity of ethyl alcohol, to 1.4, the specificgravity of a 40 percent calcium chloride solution. it is, of course,unlikely that any naturally-occurring densities or specific gravities aslow as that of ethyl alcohol will be encountered in subsurfaceenvironments. It is not impossible, however, to encounter subsurfaceenvironments having a specific gravity of up to or even more than thespecific gravity of a saturated solution of sodium chloride, forinstance, in deep salt mine pumping operations.

HO. 3 is a graph showing the allowable density differences for strandsof various lengths or depths calculated for five different ratios ofT/R, or the thickness of a nylon coating on the strand divided by theradius of the strand.

These calculations are based on the formula o' lG'B/ TAD where o-= thestrength of the plastic material of the jacket 1 the length of strand tobe used g= the gravitational constant R the radius of the strand T= thethickness of the plastic jacket AD the difference in density between theenvironment and the corrosion inhibiting liquid to be used It will berecognized that in order to avoid damage to the jacket of the strand itis absolutely essential that the difference in density between theenvironment and the corrosion-inhibiting liquid shall not exceed theallowable difference calculated from the strength of the jacket and thedepth of well or length of strand to be used. Preferably, of course, thedifference in densities will be arranged to be much less in order toprovide an acceptable safety factor.

In addition, it is very desirable that the density, or specific gravity,of the corrosion inhibitor be somewhat greater than that of theenvironment in order to aid in overcoming head loss or frictional lossesin passage of the corrosion-inhibiting liquid through the strand buteven more importantly to enable continued operation of the corrosionprotection system if the plastic jacket is breached at a point above thebottom of the strand. If the jacket should be breached through somephysical or other means between the top and the bottom of the strand andthe specific gravity, or density, of the corrosion inhibitor is greaterthan that of the environment some of the corrosion inhibitor will escapefrom the breach but the remainder will continue down into the lowerportions of the strand. If, however, the specific gravity, or density,of the corrosion inhibitor is less than that of the environment, eventhough within the allowable limits to prevent damage to the jacket,most, if not all, of the corrosion inhibitor will tend to escape fromthe breach and the environmental liquid will tend to enter the strand atthe breach and collect in the lower portions of the strand completelydefeating the purpose of the corrosion inhibitor.

It will be seen from the preceding discussion also that if the specificgravity, or density, of the corrosion inhibitor is somewhat greater thanthat of the environment not only does the increased specific gravity aidin overcoming the head or friction loss of the passage of the corrosionfluid through the strand but this head or friction loss decreases thepressure at the bottom of the strand thus in effect offsetting thedensity difference between the environment and the corrosion inhibitorand allowing somewhat greater density differences than would otherwisebe suitable.

On the other hand if the specific gravity, or density, of thecorrosion-inhibiting liquid is less than that of the environment, eventhough within the normally allowable ranges of difference, because agreater pumping pressure from the pump 49 will be necessary to overcomethe head or frictional losses in the strand, there will be a greatertendency for ballooning of the jacket near the top of the strand thanwould normally be expected from the mere density difference and theallowable ranges of density difference will be correspondinglyeffectively decreased.

it will be seen, therefore, that not only is it most important that thedensity, or specific gravity, of the corrosion-inhibiting liquid besubstantially similar to that of the environment but it is mostpreferable in practically every case that the specific gravity, ordensity, of the corrosion inhibitor be somewhat greater than that of theenvironment though still within the normally allowable limits.

It has been found that contrary to normal expectations acorrosion-inhibiting fluid can be pumped either mechanically or bypressure induced by differential specific gravities through long lengthsof jacketed wire rope, strand and cable without detrimental loss ofpressure or flow volume. Since the interstices between the wires of wirestrand extend for long distances through the strand without interruptionrelatively free movement of the liquid through the strand is possible.Parallel wire strand is particularly satisfactory in this respect as theinterstices in parallel wire strand extend substantially straight alongthe longitudinal extend of the strand. The plastic jacket will often besufficient to bind the wires of the parallel wire strand together into aunitary strand, although additional binding may be used. As a practicalmatter, however, and for applications where the strand is to besubjected to considerable stress and movement it may be found moresatisfactory to provide a fairly long lay, or slight twist, to thestrand in order to bind the individual wires together and provide apractical degree of flexibility. The long lay will not significantlydecrease the flow of the corrosion-inhibiting liquid through the strand.Such strand may be fairly characterized as substantially parallel wirestrand. For some applications a so-called bundled strand wherein thewires are not compactly seated together but are loosely bound togetherby an outer binding of some suitable form such as a plastic jacket isalso very suitable for use in the present invention and can beconsidered to be a variant of parallel wire strand. While asubstantially parallel wire strand" is most effective for use in thepresent invention, a normally stranded or twisted strand or cable willalso be satisfactory particularly for intermediate lengths of cable upto several thousand feet in length. Likewise a wire rope formed fromindividual twisted wire strands may also be used. In all cases, however,the individual wires of the strand, cable or rope should not becompacted together to such a degree that the individual wires aredeformed to any great extent as the interstices between the wires wouldthen be constricted and would present a significant impediment to thefree flow of the corrosion inhibitor through the strand. It has beenfound that if there is a lay of any degree in the wires of the strand itis very advantageous to provide a differential lay to the various layersof wire of the strand, that is to say provide different lays in thevarious layers of wires as, for instance, by having opposite lays inadjacent layers of wires, as this greatly increases the voids in thestrand and provides more unrestricted flow of the corrosion inhibitors.

FIG. 4 shows in partial cutaway section a preferred form of twisted wirestrand for the present invention. This strand has a long lay justsufficient to hold the wires of the strand together and providesufficient flexibility for a flexible pumping strand. This constructionprovides fairly straight passageways between the wires of the strand forthe free passage of corrosion-inhibiting liquid. Such strand may befairly characterized as substantially parallel wire strand thoughtechnically it is not parallel wire strand as conventionally understood.Preferably the strand 17 will have several adjacent layers 61 and 63 ofwires 19 having differential lays with respect to each other to furtherincrease the flow rate of corrosion inhibitor.

It may, in some instances, be sufficient or desirable to operate thepump 49 which pumps the corrosion-inhibiting fluid into the strand onlyintermittently to periodically flush out the strand. Any suitable timingdevice can be arranged to effectuate intermittent operation of the pump.

The corrosion-inhibiting fluid may also be formulated, in someinstances, and particularly for use in deep marine environments, tocoagulate as it seeps from any abrasion or other defect in the jacket ofthe strand to supply a self-sealing or healing effect at coatingdefects.

if desired a pressure-detecting means may be mounted to detect thenormal pressure of the corrosion inhibitor within the strand 17 near theupper portion thereof or within tubing 53. If a major break then occursin the plastic jacket 2! along the strand the resultant drop in pressurewillindicate that a break has occurred. Any suitable alarm means may berigged with the pressure indicator to give an alarm when a pressure fordrop occurs. As an alternative the pressure may be maintained constant,particularly when a difference in the densities is utilized to move thecorrosion inhibitor through the strand, and the volume measured todetect any significantly increased flow rates.

If desired, the corrosion inhibitor may be directed from the end of thestrand into some associated apparatus at the end of the strand such aspump 15 in FIG. 1 before being exhausted to the environment. In thismanner sensitive parts of the associated apparatus may be protected fromcorrosion. The corrosion inhibitor may also comprise some lubricatingsubstance which may lubricate apparatus located at the end of the strandsuch as pump 15.

In some instances it may be desirable to provide a continuousintentional defect or void in the strand such as by leaving out a wirefrom a normal layer of wires in order to provide an additional path forthe flow of corrosion inhibitor through the strand.

Other plastics than nylon may be used for the outer jacket particularapplications such as, for example, polypropylene orpolytetrafluoroethylene. In some instances also it may be desirable toprovide a metallic or other armoring for the jacket to increase itsabrasion resistance and the like. 1

We claim:

1. A corrosion protection system for the protection of cables insubatmospheric corrosive environments comprising:

a. a cable composed of a collection of individual wires,

b. a flexible outer jacket surrounding said cable and partiallypermeable to corrosion inhibiting liquid at least at the terminal end,

c. a supply of a liquid having a specific gravity substantially similarto the specific gravity of the fluid constituents of the corrosiveenvironment and being corrosion inhibiting with respect to saidenvironment, and

d. means to introduce said liquid into one end of said cable within saidouter jacket at a rate sufficient to maintain a small positive pressurein said cable with respect to said corrosive environment and to replaceportions of said liquid passing from within said jacketed cable at leastat the opposite terminal end of said cable.

2. A corrosion protection system for the protection of, cables insubatmospheric corrosive environments according to claim 1 additionallycomprising:

a. reservoir means to contain said supply of corrosion-inhibitingliquid; and

b. pump means to forcibly introduce said corrosion-inhibiting liquidfrom said reservoir means into said jacketed cable.

3. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim I wherein thespecific gravity of the corrosion-inhibiting liquid is at least as greatas the specific gravity of the corrosive environment.

4. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 2 wherein theflexible outer jacket is formed of plastic.

5. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 1 wherein theliquid of (c) has a specific gravity of between 0.85 to L2.

6. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 5 wherein thespecific gravity of the corrosion-inhibiting liquid is greater than thespecific gravity of the corrosive environment.

7. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 6 wherein saidcable has several layers of wires with a difierential lay betweenlayers.

8. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 6 wherein saidcable comprises at least a semiparallel wire strand and is jacketed withaflexible nylon jacket.

9. A COl'l'OSlOll protection system for the protection of cables insubatmospheric corrosive environments according to claim 8 wherein saidcable has several layers of wires with a difierential lay betweenlayers.

10. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim I wherein saidliquid of (c) has a specific gravity of between 0.95 and 1.05.

11. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 6 wherein thespecific gravity of the corrosion-inhibiting liquid is greater than thespecific gravity of the corrosive environment.

12. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim ll wherein saidcable is attached to secondary apparatus into which saidcorrosion-inhibiting liquid is discharged in order to additionallyprotect said secondary'apparatus from corrosion.

13. A corrosion protection system for the protection of cables insubatmospheric corrosive environments accordingto claim 11 wherein saidcable has several layers of wires with a differential lay betweenlayers.

14. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 11 wherein saidcable comprises at least a semiparallel wire strand and is jacketed witha flexible nylon jacket.

15. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 14 wherein saidcable has several layers of wires with a differential lay betweenlayers.

16. A corrosion protection system for protection of cables insubatmospheric corrosive environments comprising:

a. a cable composed of a collection of individual wires;

b. a flexible outer jacket surrounding said cable;

c. a supply of corrosion-inhibiting liquid having a density selected toavoid ballooning of the jacket for the length of cable involved; and

d. means to introduce said liquid into the top of said cable within saidouter jacket at a rate sufficient to maintain a small positive pressurein said cable with respect to an outer corrosive environment and toreplace portions of said liquid passing from said jacketed cable atleast at the opposite terminal end of said cable.

17. A method for protecting plastic-jacketed cables from corrosivesubatmospheric environments comprising introducing acorrosion-inhibiting liquid having a specific gravity substantially atleast as great as the principal fluid ingredient of said corrosiveenvironment into a portion of said cable at a rate sufficient tomaintain a small positive pressure in said cable with respect to saidcorrosive environment and to replace portions of saidcorrosion-inhibiting liquid passing from within said jacketed cable atleast at an opposite terminal end of said cable.

18. A method of protecting plastic-jacketed cables from corrosivesubatmospheric environments according to claim 17 wherein saidcorrosion-inhibiting liquid is introduced into said cableintermittently.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3 ,637,341Dated January 25 1972 James B. Horton et a1 Inventor(s) It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 18, after "necessary" insert after Column 2, line26,"'form" should read from Column 5, line 11, the formula should appearas shown below:

--- o' lgR/T X A D Signed and sealed this 10th day of October 1972.,

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents ORM PO-1050 (10-69) USCOMM-DC 60376-1 69 Q u.s. GOVERNMENTPRINTING OFFICE: I969 0-356-334,

2. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 1 additionallycomprising: a. reservoir means to contain said supply ofcorrosion-inhibiting liquid; and b. pump means to forcibly introducesaid corrosion-inhibiting liquid from said reservoir means into saidjacketed cable.
 3. A corrosion protection system for the protection ofcables in subatmospheric corrosive environments according to claim 1wherein the specific gravity of the corrosion-inhibiting liquid is atleast as great as the specific gravity of the corrosive environment. 4.A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 2 wherein theflexible outer jacket is formed of plastic.
 5. A corrosion protectionsystem for the protection of cables in subatmospheric corrosiveenvironments according to claim 1 wherein the liquid of (c) has aspecific gravity of between 0.85 to 1.2.
 6. A corrosion protectionsystem for the protection of cables in subatmospheric corrosiveenvironments according to claim 5 wherein the specific gravity of thecorrosion-inhibiting liquid is greater than the specific gravity of thecorrosive environment.
 7. A corrosion protection system for theprotection of cables in subatmospheric corrosive environments accordingto claim 6 wherein said cable has several layers of wires with adifferential lay between layers.
 8. A corrosion protection system forthe protection of cables in subatmospheric corrosive environmentsaccording to claim 6 wherein said cable comprises at least asemiparallel wire strand and is jacketed with a flexible nylon jacket.9. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 8 wherein saidcable has several layers of wires with a differential lay betweenlayers.
 10. A corrosion protection system for the protection of cablesin subatmospheric corrosive environments according to claim 1 whereinsaid liquid of (c) has a specific gravity of between 0.95 and 1.05. 11.A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 6 wherein thespecific gravity of the corrosion-inhibiting liquid is greater than thespecific gravity of the corrosive environment.
 12. A corrosionprotection system for the protection of cables in subatmosphericcorrosive environments according to claim 11 wherein said cable isattached to secondAry apparatus into which said corrosion-inhibitingliquid is discharged in order to additionally protect said secondaryapparatus from corrosion.
 13. A corrosion protection system for theprotection of cables in subatmospheric corrosive environments accordingto claim 11 wherein said cable has several layers of wires with adifferential lay between layers.
 14. A corrosion protection system forthe protection of cables in subatmospheric corrosive environmentsaccording to claim 11 wherein said cable comprises at least asemiparallel wire strand and is jacketed with a flexible nylon jacket.15. A corrosion protection system for the protection of cables insubatmospheric corrosive environments according to claim 14 wherein saidcable has several layers of wires with a differential lay betweenlayers.
 16. A corrosion protection system for protection of cables insubatmospheric corrosive environments comprising: a. a cable composed ofa collection of individual wires; b. a flexible outer jacket surroundingsaid cable; c. a supply of corrosion-inhibiting liquid having a densityselected to avoid ballooning of the jacket for the length of cableinvolved; and d. means to introduce said liquid into the top of saidcable within said outer jacket at a rate sufficient to maintain a smallpositive pressure in said cable with respect to an outer corrosiveenvironment and to replace portions of said liquid passing from saidjacketed cable at least at the opposite terminal end of said cable. 17.A method for protecting plastic-jacketed cables from corrosivesubatmospheric environments comprising introducing acorrosion-inhibiting liquid having a specific gravity substantially atleast as great as the principal fluid ingredient of said corrosiveenvironment into a portion of said cable at a rate sufficient tomaintain a small positive pressure in said cable with respect to saidcorrosive environment and to replace portions of saidcorrosion-inhibiting liquid passing from within said jacketed cable atleast at an opposite terminal end of said cable.
 18. A method ofprotecting plastic-jacketed cables from corrosive subatmosphericenvironments according to claim 17 wherein said corrosion-inhibitingliquid is introduced into said cable intermittently.